1. Field of the Invention
This invention relates to a multi-purpose implement for conducting dissimilar forest and soil management activities, grapple piling (especially as related to Forest Fuel Management) and subsoiling (especially as related to soil productivity and restoration). The invention finds particular application in reforestation of newly created skid trails, landings and legacy compaction areas, as it applies to the growth and vigor of natural and planted stock trees and shrubs in reforestation projects. New impacts occur when equipment is brought into an area on a short-term basis, such as for fire-line construction, and the remedial treatment takes place shortly thereafter. The expression, “legacy compaction” as used herein refers to compaction from previous long-term activities, particularly those involving operating heavy equipment on the soil surface. Examples of situations that lead to legacy compaction include repeated travel on road fill, skid trails, dozer pile slash treatment and soil deposition from erosion that occurs over a work site at the toe of a hill. Whereas compaction from new impacts typically resides 4″–18″ below the soil surface, legacy compaction may be deeper, and also may be accompanied by hardpan formation.
2. Description of the Prior Art
Following timber harvesting, reforestation activities sometimes include grapple rake/piling and subsoiling. The objectives of grapple piling are to deal with post-timber harvest fuels reduction. Grapple piling operations are almost exclusively associated with ground based timber harvest activities, which are credited with most of the detrimental compaction. Compaction has been associated with reduced mycorrhizal abundance and diversity in certain tree species, and also with ultimate growth rates and overall alteration of vegetation type. Soil compaction issues are typically not addressed immediately following harvest activities. Subsoiling has been proven to increase the survival and growth of seedlings in areas of previous compaction, but since there is a high cost associated with subsoiling, it is considered only after multiple planting failures and determination that a hardpan has indeed developed. Once a site has been replanted multiple times and has experienced surface losses of nutrient-laden soil, efforts to vegetate the area with desired stock may be greatly impaired regardless of renewed soil infiltration. Thus, after a ground-based harvest ends, skid trails and landings can be visible for years to decades.
In conventional practice, grapple piling and subsoiling (if performed at all) are conducted in separate operations. The grapple piling is done with log loaders or excavators using rakes, buckets and tongs. In a separate operation, subsoiling is conducted with a dozer pulling an agricultural subsoiling implement or dozer-mounted ripper system. Dozer subsoiling is used to treat compacted forest soils as a last resort and is carried out as quickly as the operator can maneuver through the harvest unit. Thick brush, stumps, boulders, and standing trees can inhibit the dozer from treating all compaction in the unit. This approach to subsoiling reduces compaction, but does not allow return of organic matter of varying size to the soil. Also, mats of organic matter tend to accumulate under the agricultural implement, resulting in a loss of organic matter from the soil surface. Carelessness during the subsoiler operation can also result in accumulation of rocks and boulders on the surface.
During grapple piling, some level of decompaction and return of organic matter to the surface can be achieved by forcing rakes, buckets or tongs into the compacted soil. However, the resultant soil profile becomes mixed rather than lifted, and the presence of unconsolidated rock or boulders can result in creation of a boulder field as in the case of inattentive dozer subsoiling operation dozer operation.
Grapple type implements are well-known. For example, various patented grapple designs are disclosed by Purser (U.S. Pat. No. 4,818,005), Murr (U.S. Pat. No. 5,890,754), Wolin et al. (U.S. Pat. No. 5,975,604) and Wheeler (U.S. Pat. No. 6,176,531). These devices are designed for single-function operation and can theoretically be used to decompact soil only by means of a churning motion. However, they are not designed for subsoiling; that is, for reducing compaction while retaining the characteristics of the soil profile.
Implements designed specifically for subsoiling are described by Williams et al. (U.S. Pat. No. 4,773,340), Gabriel (U.S. Pat. No. 5,121,800), and Grimm et al. (U.S. Pat. No. 5,605,196). Certain multi-functional implements, such as the spot-cultivation device of Willis (U.S. Pat. No. 6,067,736) are described in the literature. The implement of Willis is useful for both soil ripping and for raking.
Other types of multi-functional earth-moving equipment have been disclosed in the patent literature. For example, Larson (U.S. Pat. No. 5,456,028) shows a backhoe bucket having a single ripper attached to the same coupling element that secures the bucket to the end of a hydraulically powered boom. The result is concentration of the force provided by the boom to the ripper tip. Larson depicts various embodiments for coupling the ripper to the boom, but none are amenable to use with a “quick change” connector (tool coupler). Moreover, the pivotal mount of the ripper to the back of the bucket is susceptible to eventual stress failure. In Publication No. US 2003/0167661, Larson discloses an improvement in which the ripper is secured to a tool coupler to permit its use with a wide variety of interchangeable excavation tools.
Pratt (U.S. Pat. No. 6,490,815) shows an excavating bucket having a single ripping tooth or a pair of ripping teeth projecting rearwardly from the rear wall of the bucket. By virtue of this design the motion for functional operation of the ripper is opposite that of the bucket. In making a sweeping motion, the operator is able to alternatively break up hard material and scoop it up for removal.